Methods

Cross-sectional surveys were carried out to assess the ability of community-owned
resource persons (CORPs) to detect mosquito breeding sites and larvae in areas with
and without larviciding. Potential environmental and programmatic determinants of
habitat detection coverage and detection sensitivity of mosquito larvae were recorded
during guided walks with 64 different CORPs to assess the accuracy of data each had
collected the previous day.

Results

CORPs reported the presence of 66.2% of all aquatic habitats (1,963/2,965), but only
detected Anopheles larvae in 12.6% (29/230) of habitats that contained them. Detection sensitivity was
particularly low for late-stage Anopheles (2.7%, 3/111), the most direct programmatic indicator of malaria vector productivity.
Whether a CORP found a wet habitat or not was associated with his/her unfamiliarity
with the area (Odds Ratio (OR) [95% confidence interval (CI)] = 0.16 [0.130, 0.203],
P < 0.001), the habitat type (P < 0.001) or a fence around the compound (OR [95%CI]
= 0.50 [0.386, 0.646], P < 0.001). The majority of mosquito larvae (Anophelines 57.8%
(133/230) and Culicines 55.9% (461/825) were not reported because their habitats were
not found. The only factor affecting detection of Anopheline larvae in habitats that
were reported by CORPs was larviciding, which reduced sensitivity (OR [95%CI] = 0.37
[0.142, 0.965], P = 0.042).

Conclusions

Accessibility of habitats in urban settings presents a major challenge because the
majority of compounds are fenced for security reasons. Furthermore, CORPs under-reported
larvae especially where larvicides were applied. This UMCP system for larval surveillance
in cities must be urgently revised to improve access to enclosed compounds and the
sensitivity with which habitats are searched for larvae.